A motor is an apparatus which obtains a rotary force from electrical energy, and includes a stator and a rotor. The rotor is configured to electromagnetically interact with the stator, and rotates by a force acting between a magnetic field and current flowing in a coil.
Permanent magnet motors which use a permanent magnet to generate a magnetic field may be classified as a surface mounted permanent magnet motor, an interior type permanent magnet motor, and a spoke type permanent magnet motor.
Among these, the spoke type permanent magnet motor may generate high torque and high output due to structurally high magnetic flux density, and is able to miniaturize a motor with respect to the same output. The spoke type permanent magnet motor may be applied to a driving motor of a washing machine, a driving motor of an electric vehicle, and a driving motor of a small generator, which require high torque and high output characteristics.
In general, a rotor of the spoke type permanent magnet motor includes a plurality of permanent magnets radially disposed about a rotation axis, a plurality of rotor cores disposed between each of the permanent magnets, and a molding unit which supports the plurality of rotor cores and the plurality of magnets.
In a conventional case, to prevent a defect from occurring during injection molding due to magnetism of the magnets, the plurality of magnets in an unmagnetized state were accommodated in a mold while being alternately disposed with the plurality of rotor cores and were injection molded with a resin. The magnets were magnetized after being injection molded. In this case, since a magnetizer and the magnets may be spaced as much as a thickness of the molding unit apart, the magnets may not be magnetized to a desired strength. Thus, a decline in efficiency of magnetization caused a reduced performance of a motor.